Known manual pathogen detection methods in research and clinical laboratories tend to have low accuracy, low sensitivity to pathogens and are subject to human error, both in carrying out the methods and in interpreting the results. Other methods, e.g. culturing methods, are not suitable for many pathogens. For example, tuberculosis has a very slow growth rate, which makes detection not easy or even not possible.
One immunologic method, which identifies an organism with a known antiserum, is widely used for pathogen detection. The accuracy of the method is relatively high but the sensitivity is relatively low, e.g. it needs about one million antigen-antibody complexes to clearly indicate the results. There are a number of other disadvantages of this method, which are known.
In a standard enzyme ELISA method for immunoassay, a tray with a plurality of wells, e.g. 96 wells, containing appropriate antibodies, is used. One of the wells is used as a positive control (with a positive antigen), while the remaining wells are used for testing patient's sera. After addition of the serum samples, the wells are washed and a second antibody, which carries an enzyme, is added to the wells. After washing again, a substrate is added. The substrate and enzyme react, with a colour reaction. The colour yield from the reaction is indicative of the presence of the pathogen. The method is rife with possibilities for error. Human error can lead to some wells being washed twice or not at all, having reagents added twice or not at all, or wells being inadvertently contaminated with extraneous materials. For example, overwashing tends to flush all the components and create a false negative result, while an incomplete wash will provide detection from non-binding materials and yield false positive results. The control well can give no assurance that the results from any other well is indicative of the presence or otherwise of the pathogen under investigation. Additionally, colour differences from well to well give additional uncertainties with respect to interpretation of the results.
Most of the previous tests are demanding of time, skill and concentration. So much so, that in many jurisdictions the number of tests that can be conducted by one technician is limited by regulation. This serves to raise the cost of testing, as it is so labour dependent.
For all the above reasons, and more, a new method of detecting pathogens is desirable, which is accurate, reproducible, and is sensitive to determining if there is an error in the method.